Palladium (II) catalyzed polymerization of norbornene and acrylates

ABSTRACT

Homopolymers or copolymers of acrylates, homopolymers or copolymers of norbornenes, and copolymers of acrylates with norbornenes, may be prepared by contacting acrylate and/or norbornene monomer reactant under polymerization conditions and in the presence of a solvent with a catalyst system consisting essentially of a Pd(II) dimer component having the formula: [(L)Pd(R)(X)] 2 , where L is a monodentate phosphorus or nitrogen ligand, X is an anionic group, and R is an alkyl or aryl group.

RELATED APPLICATIONS

This application is a continuation-in-part of Ser. No. 09/565,137, filedMay 5, 2000, now U.S. Pat. No. 6,300,440, which is a division of Ser.No. 09/990,070, filed Jun. 17, 1998, now U.S. Pat. No. 6,111,041, whichclaims the benefit of U.S. Provisional No. 60/050,107, filed Jun. 18,1997.

FIELD OF THE INVENTION

This invention relates to a novel catalyst that is suitable for use inthe homopolymerization of norbornenes, in the homopolymerization ofacrylates, and in the copolymerization of norbornenes with acrylates.The invention relates, further, to a process for homopolymerizingnorbornenes and acrylates using the present catalyst, to a process forcopolymerizing norbornenes with acrylates using the present catalyst,and to novel copolymers of norbornenes with acrylates.

BACKGROUND OF THE INVENTION

Considerable interest has existed in the copolymerization of acrylateswith norbornenes because of the potential benefits of combining theuseful properties of the homopolymers of the two monomers. For example,polyacrylates are valued for their extreme hardness and adhesiveproperties, and are used to form clear, glass-like materials such asLucite™ and Plexiglas™. Polynorbornenes, on the other hand, are capableof resisting high temperatures and, thus, typically are employed inapplications that necessitate high-temperature stability.

Polymerization of acrylic derivatives is disclosed, for example, in U.S.Pat. No. 4,849,488. In that patent, certain phosphorus compounds areused as polymerization catalysts. Preferred acrylic derivatives that arepolymerized in accordance with that patent are acrylates andmethacrylates of monovalent and polyvalent alcohols. Copolymers of atleast two different acrylic derivatives are also disclosed. There is nodisclosure in that patent relevant to the possibility of copolymerizingan acrylic derivative with norbornene or a norbornene derivative.

Until the present invention, attempts to copolymerize acrylates withnorbornenes have met with modest success because of a disparity in themechanisms by which the respective monomers polymerize. U.S. Pat. No.3,697,490, for example, discloses copolymers of alkoxy alkyl acrylates,alkyl acrylates and substituted norbornene, wherein the copolymerscontain only about 0.5 to about 5.5 percent by weight substitutednorbornene compounds. The copolymers described in that patent typicallyare prepared in batch reactions, or the monomers may be proportioned toa reactor containing water and other desired polymerization additives.The patent indicates that best results are generally obtained atpolymerization temperatures in the range of 5° C. to 50° C. in thepresence of water containing a free radical generating catalyst andsurface active agents.

U.S. Pat. No. 6,034,259 broadly discloses a process for polymerizingethylene, acyclic olefins, and/or selected cyclic olefins, andoptionally selected olefinic esters or carboxylic acids. Thepolymerization reactions are catalyzed by selected transition metalcompounds, and sometimes other co-catalysts. Also described in thatpatent is the synthesis of linear alpha-olefins by the oligomerizationof ethylene using as a catalyst system a combination of a nickelcompound having a selected alpha-diimine ligand and a selected Lewis orBronsted acid, or by contacting selected alpha-diimine complexes withethylene. That patent also discloses polymerization of substitutednorbornenes using the disclosed alpha-diimine-containing catalystssystems.

Japanese publication JP040063810 relates to copolymers that containunits derived from three essential monomers, namely: (i) an acrylicester and/or methacrylic ester monomer, (2) a monomer that possesses anorbornene skeleton, and (iii) a monomer that can be radical-polymerizedwith the monomer that contains the norbornene skeleton. The copolymersmust contain from about 0.5 to about 35 mole % of units derived fromradical-polymerizable monomer (iii). The compounds that are disclosed asbeing suitable for use as the monomer (iii) include esters of maleicacid and an aliphatic alcohol which contains from 1 to 12 carbon atoms,maleic anhydride, N-substituted maleimides, α-cyanocinnamic acid, estersof α-cyanocinnamic acid and an aliphatic alcohol which contains from 1to 12 carbon atoms, and esters of fumaric acid and an aliphatic alcoholwhich contains from 1 to 12 carbon atoms. The copolymerization reactionthat is described in the Japanese publication typically is conducted inthe presence of a free radical polymerization initiator, such as acetylperoxide, benzoyl peroxide, 2,2′-azobiscyclopropylpropionitrile, or thelike.

Typically, acrylates polymerize in the presence of radical or anionicinitiators, whereas norbornenes do not follow radical pathways andnormally are polymerized by cationic or insertion mechanisms. Therefore,in order to affect the copolymerization of acrylates with norbornenes,it was necessary to develop a catalyst system that would be effectivefor polymerizing both types of monomers.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a catalyst systemthat is capable of copolymerizing acrylates with norbornenes.

It is another object to provide a catalyst system that is useful for thehomopolymerization of both acrylate monomers and norbornenes.

It is yet another object to provide a novel catalyst system that isuseful both for the homopolymerizing of acrylate monomers and norbornenemonomers, and for the copolymerization of acrylates with norbornenes.

Still another object of the invention is to provide novel copolymers ofacrylates with norbornenes.

DETAILED DESCRIPTION OF THE INVENTION

The above and other objects and advantages of the invention areaccomplished in one embodiment by providing a Pd(II)-based catalystsystem which homopolymerizes acrylates to high molecular weightpolymers, which homopolymerizes norbornenes to polymers, and whichcopolymerizes acrylates with norbornenes to high molecular weightpolymers. The copolymers prepared in accordance with this invention arecharacterized by advantages and properties attributable to therespective acrylate and norbornene monomers from which they are derived.The copolymers can be tailored in norbornene to acrylate ratio byvarying the ratio of the respective monomers in the reaction mixture andby varying the ligands utilized in the catalyst system.

The copolymers can be prepared simply by reacting one or more acrylatemonomers with one or more norbornene monomers in the presence of thepresent Pd(II)-based catalyst system. The acrylate and norbornenemonomers are the only essential monomers, although additional monomersmay be added to the polymerization mixture, provided that they do notinterfere with the desired polymerization. Thus, while there may be someinstances where it would be desirable to add monomers that can beradical-polymerized with the norbornene monomer, such as the monomersdescribed above in connection Japanese publication JP040063810 asradical-polymerizable monomer (iii), it is preferred to prepare thecopolymers of the present invention in the absence of such addedmonomers.

As used in this specification and claims, the terms “acrylates” is meantto include compounds of the general formula H₂C═CHCOOR, where R is analkyl group, such as methyl (CH₃), ethyl (CH₂CH₃), propyl (CH₂CH₂CH₃),n-butyl (CH₂CH₂CH₂CH₃) or t-butyl (C—(CH₃)₃), or an aryl group, such asphenyl (C₆H₆) or p-tolyl (C₇H₈). Other acrylates which do not conform tothe above formula, but which are nonetheless suitable for use in thepresent invention and are intended to be included within the scope ofthe term “acrylates”, include such acrylates as 2-hydroxy ethylmethacrylate and methyl methacrylate. Specific, non-limiting examples ofacrylates contemplated for use in the present invention include methylacrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, t-butylacrylate, acrylamide, 2-hydroxy ethyl methacrylate, methyl methacrylate,acrolein, ethyl methacrylate, acryloyl chloride and phenyl acrylate.

The term “norbornenes” is meant to include norbornene, as well asnorbornene derivatives, such as norbomadiene and compounds conforming tothe general formulas 5-norbornene-2-R^(1a), 5-norbornene-2,2-R^(1a),5-norbornene-3-R^(1a), 5-norbornene-3,3-R^(1a), 5-norbornene-2,3-R^(1a),or 5-norbornene-2-R^(1a)-3-R^(1b), where R^(1a) and R^(1b),independently, represent an alkyl or aryl group. Specific, non-limitingexamples of norbornenes contemplated for use in the present inventioninclude norbornene, 5-norbornene-2-methanol,cis-5-norbornene-endo-2,3-dicarboxylic anhydride,5-norbornene-2,2-dimethanol, 5-norbornen-2-ol, norbornadiene,5-norbornene-2,3-diphenyl, cis-5-norbornene-endo-2,3-dicarboxylic aciddimethyl ester, 5-norbornen-2-yl-acetate and5-norbornene-2-carboxyaldehyde.

The Pd(II)-based catalyst system of the present invention is a dimercatalyst that may be characterized by the formula [(L)Pd(R)(X)]₂. Inthis dimer catalyst, L is a monodentate phosphorus or nitrogen ligand.In general, suitable monodentate phosphorus ligands are those thatconform to the formula R² ₃P, where R² is alkyl and/or aryl group.Non-limiting examples of such monodentate phosphorus ligands includetriphenyl phosphine (PPh₃), tricyclohexyl phosphine (PCy₃), trimethylphosphine (PMe₃), triethyl phosphine (PEt₃), tri-n-propyl phosphine(P(n-Pr)₃), tri-n-butyl phosphine (P(n-Bu)₃), tri-t-butyl phosphine(P(t-Bu)₃) and tri-p-tolyl phosphine (P(p-Tol)₃). Specific, non-limitingexamples of mixed alkyl and aryl phosphines that are suitable for use inthe invention include methyldiphenyl phosphine (P(Me)(Ph)₂),phenyldimethyl phosphine (PPh(Me)₂), ethyldiphenyl phosphine(P(Et)(Ph)₂), and phenyldiethyl phosphine (PPh(Et)₂).

Generally, monodentate nitrogen ligands which may be used in the presentinvention are aromatic or heterocyclic amines, such as pyridine, t-butylpyridine, aniline, trimethyl aniline and imidazole, or compounds thatconform to the formula R₃N, where R₃ is an alkyl group, such as methyl(CH₃), ethyl (CH₂CH₃), propyl (CH₂CH₂CH₃), n-butyl (CH₂CH₂CH₂CH₃), ort-butyl (C—(CH₃)₃), or an aryl group, such as phenyl (C₆H₆) or p-tolyl(C₇H₈).

X is an anionic group, such as chlorine or bromine, or a carboxylate,such as acetate, propionate, trifluoroacetate, and benzoate; and R is analkyl group, such as methyl (CH₃), ethyl (CH₂CH₃), propyl (CH₂CH₂CH₃),n-butyl (CH₂CH₂CH₂CH₃), or t-butyl (C—(CH₃)₃), or an aryl group, such asphenyl (C₆H₆) or p-tolyl (C₇H₈).

Typically, the catalyst is formed by reaction of 1 equivalent of themonodentate ligand with [(1,5-cyclooctadiene)Pd(Me)(X)] in situ, asillustrated by the equation (using X=chlorine):

Catalyst formation may be monitored by ¹H and ³¹P{¹H} NMR. For the PCy₃analog, the movement of the methyl signal in the proton spectrum from asinglet at 1.12 ppm in the starting material to a triplet at 0.11 ppm inthe dimer upon addition of 1 equivalent PCy₃ indicates the formation ofthe desired product. Additionally, the appearance of uncoordinated1,5-cyclooctadiene signals at 5.55 and 2.34 ppm in the proton NMR and a25.6 ppm ³¹P{¹H} NMR signal for [(PCy₃)Pd(Me)(Cl)]₂ are observed.

The relevance of the alkyl (or aryl) group in the present dimer catalystsystem was explored by attempting to homopolymerize methyl acrylateusing a dimer catalyst that was devoid of alkyl (or aryl) groups. It wasfound that methyl acrylate would not polymerize when reacted in thepresence of a Pd(II) catalyst that was prepared by reacting[(1,5-cyclooctadiene)Pd(Cl)₂] with 1 equivalent of tricyclohexylphosphine (PCy₃). This indicated that the alkyl (or aryl) group isessential to the polymerization mechanism.

The copolymers of the present invention may be tailored in norbornene toacrylate ratio by varying the ratio of the respective monomers in thereaction mixture and by varying the ligands utilized in the catalystsystem. Typically, the ratio of norbornene monomer to acrylate monomerin the starting mixture is from about 100:1 to about 1:100. In preferredaspects of the invention, the ratio of norbornene monomer to acrylatemonomer that is added to the reactor is from about 10:1 to about 1:10.By varying the ratio of the norbornene monomer to acrylate monomer inthe starting mixture copolymers having a very wide range ofacrylate-derived units and norbornene-derived units can be prepared. Forexample, copolymers containing from about 5 to about 95 mole %acrylate-derived units and from about 95 to about 5 mole %norbornene-derived units may be prepared in accordance with thisinvention. In certain preferred aspects, copolymers containing fromabout 15 to about 90 mole % acrylate-derived units and from about 85 toabout 10 mole % norbornene-derived units are prepared; and in otherpreferred aspects, copolymers containing from about 25 to about 80 mole% acrylate-derived units and from about 75 to about 20 mole %norbornene-derived units are prepared. In still other preferred aspects,copolymers containing from about 35 to about 55 mole % acrylate-derivedunits and from about 45 to about 65 mole % norbornene-derived units areprepared.

The polymerization preferably is carried out in the liquid phase using asolvent, such as dichloromethane (CH₂Cl₂), benzene (C₆H₆), chlorobenzene(C₆H₅Cl) or hexane (C₆H₁₄). Other solvents that may be used as thepolymerization medium include, for example, pentane (C₅H₁₂), toluene(C₇H₈), and chloroform (CHCl₃).

The polymerization in accordance with this invention may be carried outat temperatures ranging from about 0 to about 200° C. Typically,however, the polymerization will be carried out at a temperature of fromabout 30 to about 80° C., e.g., about 50° C. The pressure at which thepolymerization is carried out is not critical.

The various aspects of the invention will be appreciated more fully inlight of the following illustrative examples:

EXAMPLE 1 Homopolymerization of Methyl Acrylate:[(1,5-cyclooctadiene)Pd(Me)-(Cl)]/PPh₃/methyl acrylate in CH₂Cl₂

In a glove box, under an inert atmosphere (nitrogen),[(1,5-cyclooctadiene)Pd-(Me)(Cl)] (0.020 g, 7.56×10⁻⁵ mol) was placedinto a 25 mL round bottom flask. To this was added 1 equivalent of PPh₃(0.020 g, 7.56×10⁻⁵ mol), followed by 3 mL of CH₂Cl₂, and the mixturewas gently swirled to dissolve the starting materials and to form aclear, colorless solution. Next, 1 g (1.2×10⁻² mol) of methyl acrylatewas added to the solution and the flask was sealed with a rubber septumand placed in a 50° C. oil bath for 24 hours. Polymer product wasobtained by precipitating in methanol, then decanting off liquid anddrying under reduced pressure at room temperature. The polymer productwas Soxhlet extracted in ether for 16 hours and dried under a vacuum.0.910 g of polymer product was obtained. The product had a numberaverage molecular weight (M_(n))=510,000 and a molecular weightdistribution (M_(w)/M_(n), where M_(w) is the weight average molecularweight)=1.3.

EXAMPLE 2 Homopolymerization of Norbornene:[(1,5-cyclooctadiene)Pd(Me)-(Cl)]/PPh₃/norbornene in benzene

In a glove box, under an inert atmosphere (nitrogen),[(1,5-cyclooctadiene)Pd-(Me)(Cl)] (0.020 g, 7.56×10⁻⁵ mol) was placedinto a 25 mL round bottom flask. To this was added 1 equivalent of PPh₃(0.020 g, 7.56×10⁻⁵ mol), followed by 3 mL of benzene, and the mixturewas gently swirled to dissolve the starting materials and to form aclear, colorless solution. Next, 1 g (1.06×10⁻² mol) of norbornene wasadded to the solution, which changed to transparent yellow inappearance. The flask was then sealed with a rubber septum and placed ina 50° C. oil bath for 24 hours. Polymer product was obtained byprecipitating in methanol, then decanting off liquid and drying underreduced pressure at room temperature. 0.983 g of polymer product wasobtained. The product had a number average molecular weight(M_(n))=2,000.

EXAMPLE 3 Homopolymerization of Methyl Acrylate:[(1,5-cyclooctadiene)Pd-(Me)(Cl)]PCy₃/methyl acrylate in CH₂Cl₂

The procedure of Example 1 was followed, except that PCy₃ (0.21 g,7.56×10⁻⁵ mol) was added to the reaction flask instead of PPh₃. 0.784 gof polymer product was obtained.

EXAMPLE 4 Homopolymerization of Norbornene:[(1,5-cyclooctadiene)Pd(Me)-(Cl)]/PCy₃/norbornene in benzene

The procedure of Example 2 was followed, except that PCy₃ (0.21 g,7.56×10⁻⁵ mol) was added to the reaction flask instead of PPh₃. 0.803 gof polymer product was obtained.

EXAMPLE 5 Homopolymerization of Methyl Acrylate:[(1,5-cyclooctadiene)Pd-(Me)(Cl)]/PMe.sub.3/methyl acrylate in CH₂Cl₂

The procedure of Example 1 was followed, except that one drop of a 1Msolution PMe₃ in toluene was added to the reaction flask instead ofPPh₃. 0.420 g of polymer product was obtained.

EXAMPLE 6 Homopolymerization of Norbornene:[(1,5-cyclooctadiene)Pd(Me)-(Cl)]/PMe.sub.3/norbornene in benzene

The procedure of Example 2 was followed, except that one drop of a 1Msolution of PMe₃ in toluene was added to the reaction flask instead ofPPh₃. 0.861 g of polymer product was obtained.

EXAMPLE 7 Homopolymerization of Methyl Acrylate:[(1,5-cyclooctadiene)Pd-(Me)(Cl)]/pyridine/methyl acrylate in CH₂Cl₂

In a glove box, under an inert atmosphere (nitrogen),[(1,5-cyclooctadiene)Pd-(Me)(Cl)] (0.035 g, 1.32×10⁻⁴ mol) was placedinto a 25 mL round bottom flask. To this was added 1 equivalent ofpyridine (0.010 g, 1.32×10⁻⁴ mol), followed by 3 mL of CH₂Cl₂, and themixture was gently swirled to dissolve the starting materials and toform a clear, colorless solution. Next, 1 g (1.2×10⁻² mol) of methylacrylate was added to the solution and the flask was sealed with arubber septum and placed in a 50° C. oil bath for 24 hours. Polymerproduct was obtained by precipitating in methanol, then decanting offliquid and drying under reduced pressure at room temperature. 0.490 g ofpolymer product was obtained.

EXAMPLE 8 Homopolymerization of Norbornene:[(1,5-cyclooctadiene)Pd-(Me)(Cl)]/pyridine/norbornene in benzene

In a glove box, under an inert atmosphere (nitrogen),[(1,5-cyclooctadiene)-Pd(Me)(Cl)] (0.035 g, 1.32×10⁻⁴ mol) was placedinto a 25 mL round bottom flask. To this was added 1 equivalent ofpyridine (0.010 g, 1.32×10⁻⁴ mol), followed by 3 mL of benzene, and themixture was gently swirled to dissolve the starting materials, thusforming a clear, colorless solution. Next, 1 g (1.2×10⁻² mol) ofnorbornene was added to the solution, which changed to transparentyellow in appearance. The flask was then sealed with a rubber septum andplaced in a 50° C. oil bath for 24 hours. Polymer product was obtainedby precipitating in methanol, then decanting off liquid and drying underreduced pressure at room temperature. 0.643 g of polymer product wasobtained.

EXAMPLE 9 Copolymer of Methyl Acrylate and Norbornene;[(1,5-cyclooctadiene)-Pd(Me)(Cl)]/PPh₃/methyl acrylate/norbornene inCH₂Cl₂(10:1 methyl acrylate:norbornene)

In a glove box, under an inert atmosphere (nitrogen),[(1,5-cyclooctadiene)-Pd(Me)(Cl)] (0.020 g, 7.56×10⁻⁵ mol) was placedinto a 25 mL round bottom flask. To this was added 1 equivalent of PPh₃(0.020 g, 7.56×10⁻⁵ mol), followed by 3 mL of CH₂Cl₂, and the mixturewas gently swirled to dissolve the starting materials, thus forming aclear, colorless solution. Next, 1.000 g (1.2×10⁻² mol) of methylacrylate and 0.113 g (1.2×10⁻³ mol) of norbornene were dissolved in eachother in a beaker, and the resulting solution was added to the flaskcontaining the dissolved [(1,5-cyclooctadiene)Pd(Me)(Cl)] and PPh₃. Theflask was sealed with a rubber septum and placed in a 50° C. oil bathfor 24 hours. Copolymer product was obtained by precipitating inmethanol, then decanting off liquid and drying under reduced pressure atroom temperature. The copolymer product was Soxhlet extracted in etherfor 16 hours and dried under a vacuum to obtain 0.120 g product. Theproduct had a number average molecular weight (M_(n))=429,700 and amolecular weight distribution (M_(w)/M_(n))=2.1.

EXAMPLE 10 Copolymer of Methyl Acrylate and Norbornene;[(1,5-cyclooctadiene)-Pd(Me)(Cl)]/PPh₃/methyl acrylate/norbornene inCH₂Cl₂ (5:1 methyl acrylate:norbornene)

The procedure of Example 9 was repeated, except that 0.800 g (9.3×10⁻³mol) of methyl acrylate and 0.175 g (1.86×10⁻³ mol) of norbornene wereadded to the reaction solution. 0.630 g of copolymer product wasobtained. The product had a number average molecular weight(M_(n))=380,000 and a molecular weight distribution (M_(w)/M_(n))=2.0.

EXAMPLE 11 Copolymer of Methyl Acrylate and Norbornene;[(1,5-cyclooctadiene)-Pd(Me)(Cl)]/PPh.sub.3/methyl acrylate/norbornenein CH₂Cl₂ (1:1 methyl acrylate:norbornene)

The procedure of Example 9 was repeated, except that 1.000 g (1.2×10⁻²mol) of methyl acrylate and 1.130 g (1.2×10⁻² mol) of norbornene wereadded to the reaction solution. 0.770 g of copolymer product wasobtained. The product had a number average molecular weight(M_(n))=60,400 and a molecular weight distribution (M_(w)/M_(n))=1.7.The product had a molar ratio of methyl methacrylate:norbornene of1:0.27 (˜21.2 mole % norbornene), as determined by ¹H NMR integration.

EXAMPLE 12 Copolymer of Methyl Acrylate and Norbornene;[(1,5-cyclooctadiene)-Pd(Me)(Cl)]/PPh₃/methyl acrylate/norbornene inCH₂Cl₂ (1:5 methyl acrylate:norbornene)

The procedure of Example 9 was repeated, except that 0.183 g (2.13×10⁻³mol) of methyl acrylate and 1.000 g (1.06×10⁻² mol) of norbornene wereadded to the reaction solution. 0.160 g of copolymer product wasobtained. The product had a number average molecular weight(M_(n))=122,000 and a molecular weight distribution (M_(w)/M_(n))=1.5.The product had a molar ratio of methyl methacrylate:norbornene of1:0.54 (˜35.1 mole % norbornene), as determined by ₁H NMR integration.

EXAMPLE 13 Copolymer of Methyl Acrylate and Norbornene;[(1,5-cyclooctadiene)-Pd(Me)(Cl)]/PPh₃/methyl acrylate/norbornene inCH₂Cl₂ (1:10 methyl acrylate:norbornene).

The procedure of Example 9 was repeated, except that 0.082 g (9.57×10⁻⁴mol) of methyl acrylate and 0.900 g (9.57×10⁻³ mol) of norbornene wereadded to the reaction solution. 0.130 g of copolymer product wasobtained. The product had a number average molecular weight(M_(n))=274,400 and a molecular weight distribution (M_(w)/M_(n))=1.5.The product had a molar ratio of methyl methacrylate:norbornene of1:1.55 (˜67.8 mole % norbornene), as determined by ¹H NMR integration.

EXAMPLE 14 Copolymer of Methyl Acrylate and Norbornene;[(1,5-cyclooctadiene)-Pd(Me)(Cl)]/PCy₃ /methyl acrylate/norbornene inCH₂Cl₂ (10:1 methyl acrylate:norbornene)

In a glove box, under an inert atmosphere (nitrogen),[(1,5-cyclooctadiene)Pd(Me)(Cl)] (0.020 g, 7.56×10⁻⁵ mol) was placedinto a 25 mL round bottom flask. To this was added 1 equivalent of PCy₃(0.021 g, 7.93×10⁻⁵ mol), followed by 3 mL of CH₂Cl₂, and the mixturewas gently swirled to dissolve the starting materials, thus forming aclear, colorless solution. Next, 1.500 g (1.7×10⁻² mol) of methylacrylate and 0.160 g (1.7×10⁻³ mol) of norbornene were dissolved in eachother in a beaker, and the resulting solution was added to the flaskcontaining the dissolved [(1,5-cyclooctadiene)Pd(Me)(Cl)] and PCy₃. Theflask was sealed with a rubber septum and placed in a 50° C. oil bathfor 24 hours. Copolymer product was obtained by precipitating inmethanol, then decanting off liquid and drying under reduced pressure atroom temperature. The copolymer product was Soxhlet extracted in etherfor 16 hours and dried under a vacuum to obtain 0.410 g product. Theproduct had a number average molecular weight (M_(n))=429,700 and amolecular weight distribution (M_(w)/M_(n))=2.1. The product had a molarratio of methyl methacrylate:norbornene of 1:0.09 (˜8.3 mole %norbornene), as determined by ¹H NMR integration.

EXAMPLE 15 Copolymer of Methyl Acrylate and Norbornene;[(1,5-cyclooctadiene)-Pd(Me)(Cl)]/PCy₃ /methyl acrylate/norbornene inCH₂Cl₂ (5:1 methyl acrylate:norbornene)

The procedure of Example 14 was repeated, except that 1.500 g (1.7×10⁻²mol) of methyl acrylate and 0.328 g (3.49×10⁻³ mol) of norbornene wereadded to the reaction solution. 0.440 of copolymer product was obtained.The product had a number average molecular weight (M_(n))=238,500 and amolecular weight distribution (M_(w)/M_(n))=1.5. The product had a molarratio of methyl methacrylate:norbornene of 1:0.11 (˜9.9 mole %norbornene), as determined by ¹H NMR integration.

EXAMPLE 16 Copolymer of Methyl Acrylate and Norbornene;[(1,5-cyclooctadiene)-Pd(Me)(Cl)]/PCy.sub.3 /methyl acrylate/norbornenein CH₂Cl₂ (1:1 methyl acrylate:norbornene)

The procedure of Example 14 was repeated, except that 1.00 g (1.2×10⁻²mol) of methyl acrylate and 1.140 g (1.2×10^(−2mol)) of norbornene wereadded to the reaction solution. 0.480 g of copolymer product wasobtained. The product had a number average molecular weight(M_(n))=39,800 and a molecular weight distribution (M_(w)/M_(n))=1.8.The product had a molar ratio of methyl methacrylate:norbornene of1:0.34 (˜25.7 mole % norbornene), as determined by ¹H NMR integration.

EXAMPLE 17 Copolymer of Methyl Acrylate and Norbornene;[(1,5-cyclooctadiene)-Pd(Me)(Cl)]/PCy₃/methyl acrylate/norbornene inCH₂Cl₂ (1:5 methyl acrylate:norbornene)

The procedure of Example 14 was repeated, except that 0.183 g (2.13×10⁻³mol) of methyl acrylate and 1.000 g (1.06×10⁻² mol) of norbornene wereadded to the reaction solution. 0.160 g of copolymer product wasobtained. The product had a number average molecular weight(M_(n))=24,000 and a molecular weight distribution (M_(w)/M_(n))=1.5.

EXAMPLE 18 Copolymer of Methyl Acrylate and Norbornene;[(1,5-cyclooctadiene)-Pd(Me)(Cl)]/PCy₃/methyl acrylate/norbornene inCH₂Cl₂ (1:10 methyl acrylate:norbornene)

The procedure of Example 14 was repeated, except that 0.137 g (1.60×10⁻³mol) of methyl acrylate and 1.500 g (1.6×10⁻² mol) of norbornene wereadded to the reaction solution. 0.040 g of copolymer product wasobtained. The product had a number average molecular weight(M_(n))=1,000.

EXAMPLE 19 Copolymer of Methyl Acrylate and Norbornene;[(1,5-cyclooctadiene)-Pd(Me)(Cl)]/PMe₃/methyl acrylate/norbornene inCH₂Cl₂ (10:1 methyl acrylate:norbornene)

In a glove box, under an inert atmosphere (nitrogen),[(1,5-cyclooctadiene)Pd(Me)(Cl)] (0.020 g, 7.56×10⁻⁵ mol) was placedinto a 25 mL round bottom flask. To this was added 1 drop of 1M PMe₃ intoluene, followed by 3 mL of CH₂Cl₂. The mixture was gently swirled todissolve the starting materials, thus forming a clear, colorlesssolution. Next, 1.500 g (1.7×10⁻² mol) of methyl acrylate and 0.160 g(1.7×10³ mol) of norbornene were dissolved in each other in a beaker,and the resulting solution was added to the flask containing the[(1,5-cyclooctadiene)Pd(Me)(Cl)] and PMe₃. The flask was sealed with arubber septum and placed in a 50° C. oil bath for 24 hours. Copolymerproduct was obtained by precipitating in methanol, then dacanting offliquid and drying under reduced pressure at room temperature. Thecopolymer product was Soxhlet extracted in ether for 16 hours and driedunder a vacuum. 0.230 g of copolymer product was obtained. The producthad a number average molecular weight (M_(n))=363,700 and a molecularweight distribution (M_(w)/M_(n))=1.4.

EXAMPLE 20 Copolymer of Methyl Acrylate and Norbornene;[(1,5-cyclooetadiene)-Pd(Me)(Cl)]/PMe₃/methyl acrylate/norbornene inCH₂Cl₂ (5:1 methyl acrylate:norbornene)

The procedure of Example 19 was repeated, except that 1.500 g (1.7×10⁻²mol) of methyl acrylate and 0.328 g (3.49×10⁻³ mol) of norbornene wereadded to the reaction solution. 0.440 g of copolymer product wasobtained. The product had a number average molecular weight(M_(n))=249,500 and a molecular weight distribution (M_(w)/M_(n))=1.6.

EXAMPLE 21 Copolymer of Methyl Acrylate and Norbornene;[(1,5-cyclooctadiene)-Pd(Me)(Cl)]/PMe₃/methyl acrylate/norbornene inCH₂Cl₂ (1:1 methyl acrylate:norbornene)

The procedure of Example 19 was repeated, except that 1.00 g (1.2×10⁻²mol) of methyl acrylate and 1.140 g (1.2×10⁻² mol) of norbornene wereadded to the reaction solution. 0.480 g of copolymer product wasobtained. The product had a number average molecular weight(M_(n))=86,400 and a molecular weight distribution (M_(w)/M_(n))=1.6.

EXAMPLE 22 Copolymer of Methyl Acrylate and Norbornene;[(1,5-cyclooctadiene)-Pd(Me)(Cl)]/PMe₃/methyl acrylate/norbornene inCH₂Cl₂ (1:5 methyl acrylate:norbornene)

The procedure of Example 19 was repeated, except that 0.183 g (2.13×10⁻³mol) of methyl acrylate and 1.000 g (1.06×10⁻² mol) of norbornene wereadded to the reaction solution. 0.206 g of copolymer product wasobtained. The product had a number average molecular weight (M_(n))−800.

EXAMPLE 23 Copolymer of Methyl Acrylate and Norbornene;[(1,5-cyclooctadiene)-Pd(Me)(Cl)]/PMe₃/methyl acrylate/norbornene inCH₂Cl₂ (1:10 methyl acrylate:norbornene)

The procedure of Example 14 was repeated, except that 0.137 g (1.60×10⁻³mol) of methyl acrylate and 1.500 g (1.6×10⁻² mol) of norbornene wereadded to the reaction solution. 0.040 g of copolymer product wasobtained. The product had a number average molecular weight (M_(n))=800.

EXAMPLE 24 Copolymer of Methyl Acrylate and Norbornene;[(1,5-cyclooctadiene)-Pd(Me)(Cl)]/pyridine/methyl acrylate/norbornene inCH₂Cl₂ (10:1 methyl acrylate:norbornene)

In a glove box, under an inert atmosphere (nitrogen),[(1,5-cyclooctadiene)Pd(Me)(Cl)] (0.035 g, 1.32×10⁻⁴ mol) was placedinto a 25 mL round bottom flask. To this was added 1 equivalent ofpyridine (0.010 g, 1.32×10⁻⁴ mol), followed by 3 mL of CH₂Cl₂. Themixture was gently swirled to dissolve the starting materials, thusforming a clear, colorless solution. Next, 1.500 g (1.7×10⁻² mol) ofmethyl acrylate and 0.160 g (1.7×10⁻³ mol) of norbornene were dissolvedin each other in a beaker, and the resulting solution was added to theflask containing the dissolved [(1,5-cyclooctadiene)Pd(Me)(Cl)] andpyridine. The flask was sealed with a rubber septum and placed in a 50°C. oil bath for 24 hours. Copolymer product was obtained byprecipitating in methanol, then decanting off liquid and drying underreduced pressure at room temperature. The copolymer product was Soxhletextracted in ether for 16 hours and dried under a vacuum. The producthad a number average molecular weight (M^(n))=23,800 and a molecularweight distribution (M_(w)/M_(n))=1.8.

EXAMPLE 25 Copolymer of Methyl Acrylate and Norbornene;[(1,5-cyclooctadiene)-Pd(Me)(Cl)]/pyridine/methyl acrylate/norbornene inCH₂Cl₂ (5:1 methyl acrylate:norbornene)

The procedure of Example 25 was repeated, except that 1.500 g (1.7×10⁻²mol) of methyl acrylate and 0.328 g (3.49×10⁻³ mol) of norbornene wereadded to the reaction solution. 0.046 g of copolymer product wasobtained. The product had a number average molecular weightM_(n))=75,300 and a molecular weight distribution (M_(w)/M_(n))=1.4.

EXAMPLE 26 Copolymer of Methyl Acrylate and Norbornene;[(1,5-cyclooctadiene)-Pd(Me)(Cl)]/pyridine/methyl acrylate/norbornene inCH₂Cl₂ (1:1 methyl acrylate:norbornene)

The procedure of Example 25 was repeated, except that 1.00 g (1.2×10⁻²mol) of methyl acrylate and 1.140 g (1.2×10⁻² mol) of norbornene wereadded to the reaction solution. The product had a number averagemolecular weight (M_(n))=8,400 and a molecular weight distribution(M_(w)/M_(n))=2.0. The product had a molar ratio of methylmethacrylate:norbornene of 1:0.23 (˜18.7 mole % norbornene), asdetermined by ¹H NMR integration.

EXAMPLE 27 Copolymer of Methyl Acrylate and Norbornene;[(1,5-cyclooctadiene)-Pd(Me)(Cl)]/pyridine/methyl acrylate/norbornene inCH₂Cl₂ (1:5 methyl acrylate:norbornene)

The procedure of Example 25 was repeated, except that 0.183 g (2.13×10⁻³mol) of methyl acrylate and 1.000 g (1.06×10⁻² mol) of norbornene wereadded to the reaction solution. 0.086 g of copolymer product wasobtained. The product had a number average molecular weight(M_(n))=75,200 and a molecular weight distribution (M_(w)/M_(n))=1.5.The product had a molar ratio of methyl methacrylate:norbornene of1:0.57 (˜36.3 mole % norbornene), as determined by ¹H NMR integration.

EXAMPLE 28 Copolymer of Methyl Acrylate and Norbornene;[(1,5-cyclooctadiene)-Pd(Me)(Cl)]/pyridine/methyl acrylate/norbornene inCH₂Cl₂ (1:10 methyl acrylate:norbornene)

The procedure of Example 25 was repeated, except that 0.082 g (9.57×10⁻⁴mol) of methyl acrylate and 1.000 g (1.06 ×10⁻² mol) of norbornene wereadded to the reaction solution. 0.072 g of copolymer product wasobtained. The product had a number average molecular weight(M_(n))=26,100 and a molecular weight distribution (M_(w)/M_(n))=1.7.The product had a molar ratio of methyl methacrylate:norbornene of1:0.71 (˜41.5 mole % norbornene), as determined by ¹H NMR integration.

EXAMPLE 29 Homopolymerization of n-Butyl Acrylate:[(1,5-cyclooctadiene)-Pd(Me)(Cl)]/PPh₃/n-butyl acrylate in chlorobenzene

In a glove box, under an inert atmosphere (nitrogen),[(1,5-cyclooctadiene)Pd(Me)(Cl)] (0.020 g, 7.56×10⁻⁵ mol) was placedinto a 25 mL round bottom flask. To this was added 1 equivalent of PPh₃(0.020 g, 7.56×10⁻⁵ mol), followed by 3 mL of chlorobenzene (C₆H₅Cl),and the mixture was gently swirled to dissolve the starting materials,thus forming a clear, colorless solution. Next, 2 g of n-butyl acrylatewas added to the solution and the flask was sealed with a rubber septumand placed in a 50° C. oil bath for 24 hours. 0.420 g of polymer productwas obtained by precipitating in methanol, then decanting off liquid anddrying under reduced pressure at room temperature. The product had anumber average molecular weight (M_(n))=627,000 and a molecular weightdistribution (M_(w)/M_(n))=1.2.

EXAMPLE 30 Copolymerization of n-Butyl Acrylate and Norbornene:[(1,5-cyclooctadiene)Pd(Me)(Cl)]/PPh₃/n-butyl acrylate/norbornene inchlorobenzene (1:1.36 n-butyl acrylate:norbornene).

In a glove box, under an inert atmosphere (nitrogen),[(1,5-cyclooctadiene)Pd(Me)(Cl)] (0.020 g, 7.56×10⁻⁵ mol) was placedinto a 25 mL round bottom flask. To this was added 1 equivalent of PPh₃(0.020 g, 7.56×10⁻⁵ mol), followed by 3 mL of chlorobenzene, and themixture was gently swirled to dissolve the starting materials, thusforming a clear, colorless solution. Next, 1.000 g (7.81×10⁻³ mol) ofn-butyl acrylate and 1.000 g (1.06×10⁻² mol) of norbornene were added tothe solution. The flask was then sealed with a rubber septum and placedin a 50° C. oil bath for 24 hours. 0.356 g of copolymer product wasobtained by precipitating in methanol, and then decanting off liquid anddrying under reduced pressure at room temperature. The product had anumber average molecular weight (M_(n))=267,800 and a molecular weightdistribution (M_(w)/M_(n))=1.5.

EXAMPLE 31 Homopolymerization of t-Butyl Acrylate:[(1,5-cyclooctadiene)-Pd(Me)(Cl)]/PPh₃/t-butyl acrylate inchlorobenzene.

In a glove box, under an inert atmosphere (nitrogen),[(1,5-cyclooctadiene)-Pd(Me)(Cl)] (0.020 g, 7.56×10⁻⁵ mol) was placedinto a 25 mL round bottom flask. To this was added 1 equivalent of PPh₃(0.020 g, 7.56×10⁻⁵ mol), followed by 3 ML of chlorobenzene (C₆H₅Cl),and the mixture was gently swirled to dissolve the starting materials,thus forming a clear, colorless solution. Next, 1.000 g (7.81×10⁻³ mol)of t-butyl acrylate was added to the solution and the flask was sealedwith a rubber septum and placed in a 50° C. oil bath for 24 hours.Polymer product was obtained by precipitating in methanol, and thendecanting off liquid and drying under reduced pressure at roomtemperature. The product had a number average molecular weight(M_(n))=550,000 and a molecular weight distribution (M_(w)/M_(n))=1.2.

EXAMPLE 32 Copolymerization of n-Butyl Acrylate and Norbornene:[(1,5-cyclo-octadiene)Pd(Me)(Cl)]/PPh₃]/t-butyl acrylate/norbornene inchlorobenzene (1:1 t-butyl acrylate:norbornene).

In a glove box, under an inert atmosphere (nitrogen),[(1,5-cyclooctadiene)Pd(Me)(Cl)] (0.020 g, 7.56×10⁻⁵ mol) was placedinto a 25 mL round bottom flask. To this was added 1 equivalent of PPh₃(0.020 g, 7.56×10⁻⁵ mol), followed by 3 ML of chlorobenzene, and themixture was gently swirled to dissolve the starting materials, thusforming a clear, colorless solution. Next, 1.000 g (7.81×10⁻³ mol) oft-butyl acrylate and 1.000 g (1.06×10⁻² mol) of norbornene were added tothe solution. The flask was then sealed with a rubber septum and placedin a 50° C. oil bath for 24 hours. Copolymer product was obtained byprecipitating in methanol, then decanting off liquid and drying underreduced pressure at room temperature

EXAMPLE 33 Homopolymerization of n-Butyl Acrylate:[(1,5-cyclooctadiene)-Pd(Me)(Cl)]/PPh₃/n-butyl acrylate in hexane

In a glove box, under an inert atmosphere (nitrogen),[(1,5-cyclooctadiene)-Pd(Me)(Cl)] (0.020 g, 7.56×10⁻⁵ mol) was placedinto a 25 mL round bottom flask. To this was added 1 equivalent of PPh₃(0.020 g, 7.56×10⁻⁵ mol), followed by 3 mL of hexane (C₆H₁₄), and themixture was gently swirled to dissolve the starting materials, thusforming a clear, colorless solution. Next, 2 g (1.56×10⁻² mol) of butylacrylate was added to the solution and the flask was sealed with arubber septum and placed in a 50° C. oil bath for 24 hours. Polymerproduct was obtained by precipitating in methanol, then decanting offliquid and drying under reduced pressure at room temperature. Theproduct had a number average molecular weight (M_(n))=127,000 and amolecular weight distribution (M_(w)/M_(n))=1.3.

EXAMPLE 34 Homopolymerization of Methyl Acrylate:[(1,5-cyclooctadiene)-Pd(Me)(Cl)]/PPh₃ methyl methacrylate in benzene

In a glove box, under an inert atmosphere (nitrogen),[(1,5-cyclooctadiene)-Pd(Me)(Cl)] (0.020 g, 7.56×10⁻⁵ mol) was placedinto a 25 mL round bottom flask. To this was added 1 equivalent of PPh₃(0.020 g, 7.56×10⁻⁵ mol), followed by 3 mL of benzene (C₆H₆), and themixture was gently swirled to dissolve the starting materials, thusforming a clear, colorless solution. Next, 2 g of methyl methacrylatewas added to the solution and the flask was sealed with a rubber septumstirred at 50° C. for 24 hours. Polymer product was obtained byprecipitating in methanol, then decanting off liquid and drying underreduced pressure at room temperature. 0.025 g of polymer product wasobtained. The product had a number average molecular weight(M_(n))=193,000 and a molecular weight distribution (M_(w)/M_(n))=1.5.

EXAMPLE 35 Homopolymerization of Ethyl Acrylate:[(1,5-cyclooctadiene)-Pd(Me)(Cl)]/PPh₃/ethyl acrylate in CH₂Cl₂

In a glove box, under an inert atmosphere (nitrogen),[(1,5-cyclooctadiene)-Pd(Me)(Cl)](0.020 g, 7.56×10⁻⁵ mol) was placedinto a 25 mL round bottom flask. To this was added 1 equivalent of PPh₃(0.020 g, 7.56×10⁻⁵ mol), followed by 3 mL of dichloromethane (CH₂Cl₂),and the mixture was gently swirled to dissolve the starting materials,thus forming a clear, colorless solution. Next, 2 g (2.0×10⁻² mol) ofethyl acrylate was added to the solution and the flask was sealed with arubber septum stirred at 50° C. for 24 hours. Polymer product wasobtained by precipitating in methanol, then decanting off liquid anddrying under reduced pressure at room temperature. 0.837 g of polymerproduct was obtained. The product had a number average molecular weight(M_(n))=127,000 and a molecular weight distribution (M_(w)/M_(n))=1.3.

TABLE 1 Methyl Acrylate/ Norbornene M_(n) Mole % Ex. No. Ligand ReactantMolar Ratio (Daltons) M_(w)/M_(n) NB  9 PPh₃ 10:1  429,700 2.1 — 10 PPh₃5:1 380,000 2.0 — 11 PPh₃ 1:1  60,400 1.7 21.2 12 PPh₃ 1:5 122,000 1.535.1 13 PPh₃  1:10 274,400 1.5 67.8 14 PCy₃ 10:1  429,700 2.1 8.3 15PCy₃ 5:1 238,500 1.5 9.9 16 PCy₃ 1:1  39,800 1.8 25.7 17 PCy₃ 1:5 24,000 1.5 — 18 PCy₃  1:10  1,000 — — 19 PMe₃ 10:1  363,700 1.4 — 20PMe₃ 5:1 249,500 1.6 — 21 PMe₃ 1:1  86,400 1.6 — 22 PMe₃ 1:5    800 — —23 PMe₃  1:10    800 — — 24 Pyridine 10:1   23,800 1.8 — 25 Pyridine 5:1 75,300 1.4 — 26 Pyridine 1:1  8,400 2.0 18.7 27 Pyridine 1:5  75,2001.5 36.3 28 Pyridine  1:10  26,100 1.7 41.5

As discussed briefly above, and as will be more readily apparent in viewof the foregoing examples, the properties of the copolymers can betailored by varying the ratio of the respective monomers in the reactionmixture and by varying the catalyst system. Varying the ratio ofacrylate monomer to norbornene monomer affects the properties of thecopolymers in that increasing the ratio of one of the monomer reactantsincreases its presence in the copolymer product. In instances of a veryhigh ratio of one monomer relative to the other (for example, in 10:1and 1:10 monomer ratio reactions) the resulting copolymer productconsists of long strings of repeating units of the abundant monomer witha few units of the less abundant monomer. Thus, polymer products havinga high acrylate content, e.g., high methyl content, tend to be somewhattacky, whereas polymers having a high norbornene content are whitepowdery substances. Varying the ligand used in the reaction and/orvarying the reactant monomer ratio also affects the molecular weight ofthe copolymer product. Thus, referring to the examples and Table 1, itcan be seen that the mole % of norbornene in the copolymer productincreased as the ratio of acrylate monomer to norbornene monomer in thereaction decreased from 10:1 to 1:1 when PPh₃ was used as the ligand(Examples 11-13), when PCy₃ was used as the ligand (Examples 14-16), andwhen pyridine was used as the ligand (Examples 26-28). Similarly, it canbe seen that the molecular weight of the copolymer product increased asthe ratio of acrylate monomer to norbornene monomer increased from 1:1to 10:1 when PPh₃ was used as the ligand (Examples 9-11), when PCy₃ wasused as the ligand (Examples 14-16), and when PMe₃ was used as theligand (Examples 19-21). It also can be seen that the use of pyridine asthe ligand (Examples 24-28) generally resulted in the production oflower molecular weight copolymers, whereas the use of triphenylphosphine as the ligand (Examples 9-13) tended to produce highermolecular weight copolymers.

While the present invention has been described and exemplified above, itis to be understood that the invention is not limited to the details ofthe illustrative embodiments and examples, but may be embodied withvarious changes and modifications which may occur to those skilled inthe art, without departing from the spirit and scope of the inventiondefined in the following claims.

What is claimed is:
 1. An acrylate-norbornene copolymer consistingessentially of from about 15 to about 90 mole % acrylate-derived unitsand from about 85 to about 10 mole percent norbornene-derived units. 2.The copolymer according to claim 1, consisting essentially of from about25 to about 80 mole % acrylate-derived units and from about 75 to about20 mole % norbornene-derived units.
 3. The copolymer according to claim1, consisting essentially of from about 35 to about 55 mole %acrylate-derived units and from about 65 to about 45 mole %norbornene-derived units.
 4. An acrylate-norbornene copolymer comprisingfrom about 15 to about 90 mole % acrylate-derived units and from about85 to about 10 mole % norbornene-derived units, said copolymer beingsubstantially free from units that are derived from a compound that canbe radical-polymerized with norbornene.
 5. The copolymer according toclaim 4, wherein said copolymer is substantially free from units thatare derived from a member selected from the group consisting of estersof maleic acid and an aliphatic alcohol which contains from 1 to 12carbon atoms, maleic anhydride, N-substituted maleimides,α-cyanocinnamic acid, esters of α-cyanocinnamic acid and an aliphaticalcohol which contains from 1 to 12 carbon atoms, and esters of fumaricacid and an aliphatic alcohol which contains from 1 to 12 carbon atoms.